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godlygeek · godlygeek · commit 2082edb57065 · 2026-06-11T15:51:39.000-04:00
diff --git a/Objects/obmalloc.c b/Objects/obmalloc.c
@@ -363,6 +363,7 @@ _PyObject_MiRealloc(void *ctx, void *ptr, size_t nbytes)
         _mi_memcpy((char*)newp + offset, (char*)ptr + offset, copy_size - offset);
     }
     else {
+        // memcpy(dst, NULL, 0) is undefined behavior. Guard against it.
         if mi_likely(ptr) {
             _mi_memcpy(newp, ptr, copy_size);
         }

Original file line number	Diff line number	Diff line change
`@@ -363,6 +363,7 @@ _PyObject_MiRealloc(void ctx, void ptr, size_t nbytes)`
`363`	`363`	`_mi_memcpy((char)newp + offset, (char)ptr + offset, copy_size - offset);`
`364`	`364`	`}`
`365`	`365`	`else {`
	`366`	`+ // memcpy(dst, NULL, 0) is undefined behavior. Guard against it.`
`366`	`367`	`if mi_likely(ptr) {`
`367`	`368`	`_mi_memcpy(newp, ptr, copy_size);`
`368`	`369`	`}`